Reduced mesophyll conductance by cell wall thickening and chloroplasts decreasing driven the decline of photosynthesis under sole NH4+ supply

The relationship between nitrogen (N) sources and photosynthetic capacity of leaf differs between species. However, the leaf anatomical variabilities related to photosynthesis (A) of shrubs under different forms of N remain imperfectly known. Here, Lonicera Japonica (a shrub) was grown hydroponically in the presence of three forms of N (sole NH4+, 50%/50% NH4+/NO3– and sole NO3–). A and photosynthetic N use efficiency significantly decreased under sole NH4+ supply, in parallel with down-regulated stomatal conductance (gs), mesophyll conductance (gm), and electron transfer rate (J). Up to the total A decline of 41.28% in sole NH4+ supply (compare with sole NO3–), the gm attributed to 60.3% of the total limitations. Besides, the decreased internal air space explained the increase of gas-phase resistance, and the increased liquid-phase resistance in sole NH4+ supply was ascribed to the thicker cell wall thickness (Tcw) and decreased chloroplasts exposed surface area per unit leaf area (Sc/S). The discrepancy of Sc/S could be interpreted by the altered chloroplasts numbers and the distance between adjacent chloroplasts (Dchl-chl). These results indicate the alteration of Tcw and chloroplast numbers were the main causes of the difference in gm in coping with varied N sources.

Analytical and Experimental Investigation of a Triangular-Channeled Solar Water Heater

Utilization of solar energy is increasing in different states of the world, and the sun is regarded as the largest source of continuous and coherent energy. In the present study, a novel configuration of a v-corrugated solar collector with triangular channels for domestic water heating has been analytically investigated. A mathematical model based on effectiveness-NTU method is established to thermally examine the collector. Additionally, the heat losses from the body of the collector, useful energy from the collector and solar efficiency have been calculated analytically over different operating parameters. The effects of mass flow rate and solar heat flux on water outlet temperature are evaluated analytically and compared with the experimental results. Moreover, the study includes the experimental and theoretical investigation of the heat exchange effectiveness and thermal efficiency of the proposed absorber. The study shows that high temperature and high performance can be obtained from this collector as more heat energy can be collected by using triangular channels because all the three sides of these channels are exposed to solar radiations at the same time. Therefore, these channels will enhance the collector exposed surface area and thereby increase the solar efficiency and overall performance of the system.

Nano-SiO2/DBN: an efficacious and reusable catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran derivatives

Background The nano-sized particles enhance the exposed surface area of the active part of the catalyst, thereby increasing the contact between precursors and catalyst considerably. In this study, nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en was synthesized, characterized and used as a heterogeneous nanocatalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives. Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, Brunauer–Emmett–Teller plot, Energy Dispersive X-ray Spectroscopy and Thermo Gravimetric Analysis were used to discern nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en. Results Tetrahydrobenzo[b]pyrans were synthesized by using nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en via one-pot three-component condensation of malononitrile, aldehydes and dimedone in H2O/EtOH at 60 °C. The results indicate that tetrahydrobenzo[b]pyrans were synthesized in good to high yields and short reaction times. Conclusions The fundamental privileges of this method are short reaction time, plain procedure, recyclability of catalyst and high yields of products.

Nano-SiO2/DBN: An efficacious and reusable catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran derivatives

Background: The nano-sized particles enhance the exposed surface area of the active part of the catalyst, thereby increasing the contact between precursors and catalyst considerably. In this study, nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en was synthesized, characterized and used as a heterogeneous nanocatalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives. Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, Brunauer–Emmett–Teller plot, Energy Dispersive X-ray Spectroscopy and Thermo Gravimetric Analysis were used to discern nano- SiO2/1,5-diazabicyclo[4.3.0]non-5-en.Results: Tetrahydrobenzo[b]pyrans were synthesized by using nano- SiO2/1,5-diazabicyclo[4.3.0]non-5-en via one-pot three-component condensation of malononitrile, aldehydes and dimedone in H2O/EtOH at 60 °C. The results indicate that tetrahydrobenzo[b]pyrans were synthesized in good to high yields and short reaction times.Conclusions: The fundamental privileges of this method are short reaction time, plain procedure, recyclability of catalyst and high yields of products.

Correction: Rajasekharan, S., et al. Effect of Exposed Surface Area, Volume and Environmental pH on the Calcium Ion Release of Three Commercially Available Tricalcium Silicate Based Dental Cements. Materials 2018, 11, 123

The authors wish to make the following correction to the paper [...]

Two-Dimensional Materials and Composites as Potential Water Splitting Photocatalysts: A Review

Hydrogen production via water dissociation under exposure to sunlight has emanated as an environmentally friendly, highly productive and expedient process to overcome the energy production and consumption gap, while evading the challenges of fossil fuel depletion and ecological contamination. Various classes of materials are being explored as viable photocatalysts to achieve this purpose, among which, the two-dimensional materials have emerged as prominent candidates, having the intrinsic advantages of visible light sensitivity; structural and chemical tuneability; extensively exposed surface area; and flexibility to form composites and heterostructures. In an abridged manner, the common types of 2D photocatalysts, their position as potential contenders in photocatalytic processes, their derivatives and their modifications are described herein, as it all applies to achieving the coveted chemical and physical properties by fine-tuning the synthesis techniques, precursor ingredients and nano-structural alterations.

CeO2 for Water Remediation: Comparison of Various Advanced Oxidation Processes

Three different Advanced Oxidation Processes (AOPs) have been investigated for the degradation of the imidacloprid pesticide in water: photocatalysis, Fenton and photo-Fenton reactions. For these tests, we have compared the performance of two types of CeO2, employed as a non-conventional photocatalyst/Fenton-like material. The first one has been prepared by chemical precipitation with KOH, while the second one has been obtained by exposing the as-synthetized CeO2 to solar irradiation in H2 stream. This latter treatment led to obtain a more defective CeO2 (coded as “grey CeO2”) with the formation of Ce3+ sites on the surface of CeO2, as determined by Raman and X-ray Photoelectron Spectroscopy (XPS) characterizations. This peculiar feature has been demonstrated as beneficial for the solar photo–Fenton reaction, with the best performance exhibited by the grey CeO2. On the contrary, the bare CeO2 showed a photocatalytic activity higher with respect to the grey CeO2, due to the higher exposed surface area and the lower band-gap. The easy synthetic procedures of CeO2 reported here, allows to tune and modify the physico-chemical properties of CeO2, allowing a choice of different CeO2 samples on the basis of the specific AOPs for water remediation. Furthermore, neither of the samples have shown any critical toxicity.